Reinforcement for concrete flat slabs.



W. C. EDWARDS, JR.

REINFORCEMENT FOR CONCRETE FLAT SLABS. APPLICATION riLnn JULY 31. m2

1,057,531 Patented Apr. 1, 1918.

15 SHEETS SHEET l W. 0. EDWARDS, JR. REINFORCEMENT FOR CONCRETE FLATSLABS.

- Patented Apr. 1, 1913.

3 SHEBTSSHEET 3.

APPLICATION FILED JULY 31. 1912.

Q 04/ uuuuuuuuuoo rinrrnn earns rarnnr onnroir.

WILLIAM C. EDWARDS, JR., OF KANSAS CITY, MISSOURI.

REINFORCEMENT FOR CONCRETE FLAT SLABS.

Application filed July 31,

To all LU/MINI, it may concern:

Be it known that I, uau/nu C. Eownnns, Jr., a citizen of the UnitedStates of America, residing at Kansas City in the county of Jackson. andState of Missouri. have invented certain new and useful Improve-- mentsin Reinforcements for Concrete Flat Slabs; and I do hereby declare thatthe following is a full, clear, and exact descrip-.

tion of the invention, such as will enable others to make and use thesame, reference being had to'the accompanying drawings, forming a partof this specification.

The principal objects of the invention are, to provide an arrangement ofsteel reinforcement in flat slab concrete construction so that allstresses will be provided for,

and a true monolithic structure obtained; 'to carry the tension steelover the columns in a single layer or plate thereby increasing theeffective dept-h at this criticalpoint;

to care-for all tension stresses in flat slab construction by means ofreinforcing members integral with and radiating from a metallic hub prdisk situated in said slab concentric with the axis of a supportingcolumn. 4

The flat slab concrete floor by its elimination, of beams and girdersaffords many adlarging the column heads, increased resistance in shearand bending is obtained. 7

In the'drawings, Figure 1.. is a plan or top view of a partiallycompleted reinforcement for concrete fiat slab construction. Fig. 2.shows a vertical section of a completed concrete flat slab taken on aliliethrough the centers of two rectangularly positioned columns inFig. 1. such asA and B. Fig. 3. shows a side view of the reinforcingrods seen in Fig. 2. linked to the rim of the unit, cantaliverreinforcing de:

vice at a column and radiating outward, to-

ward and under the eantaliver reinforce- Specification of LettersPatent.

llatcntcd Apr. 1. M113.

1912. Serial No. 712,436.

vertical section of a completed concrete fiat- Slab taken through theaxis of a column in Fig. 1. and on a. line radiating therefrom andcrossing the slab portion between columns as seen in F ig. 2. Fig. 5.shows a side view of the reinforcing rods seen in Fig. 4. linked to theunit cantaliver reinforcement at the columns and radiating outwardtherefrom and crossing the upper part of the slab between outer columnsas seenin Fig. 1 and Fig. 2. Fig. 6. represents a vertical cross-sectiontaken through the rim portion of the unit device of the slabreinforcement as seen at in Fig. 1. Fig. 7.

represents a section taken along the line. wm in Fig. 6. Fig. 8. is aview'showing' the approximate location of the line of inflection forimaginary beams radiating from the axis of a supporting column. Fig. 9.shows a perspective viewof a fabricated steel structural unit cantaliverreinforcing device of wheel-like construction for the fiat slab as seenin Fig. 1.-placed concentric with the columns. F ig. 10. shows a blankslitted metal plate from which is fabricated a modified form ofreinforcement to that seen in. Fig. 9. Fig. 11. represents a plan viewof that portion of the metal plate included within the dotted lines inFig. 10, shown in its finished fabricated cOndit-iDn. Fig. 12.represents a side view of the sec-- tional reinforcing device seen inFig. 11. Fig. 13. shows a section through the center of a reinforcingdevice formed from, the slitted plate seen in Fig. 10 and shown in its-finished condition by views indicated in Figs. 11 and 1.2,together'with portions of the slab rod reinforcement engaged there-With' and means for preventing disengagement of the said rod members.

ment over an adjacent column. Fig. 4-. shows a Similar numerals ofreference indicate corresponding parts in all figures of the drawings. I

Referringto the drawings: In Fig. 1. is

seen a plan view of a partially completed reinforcement. for monolithicconcrete lat slab construction,"consisting of a number of fabricatedwheel-like"stee'i- .unit- 'cantaliver reinforcing d'evices'flt), Fig.9.)each placed horizontally with theiri hub portions 21 concentric withthe. vertical aids of a supporting column. A plurality of spoke members22 mains-from the hub mem ber 21, said spoke inembers terminate; attheir ,outer ends" in the rim or band 23,-leaving the openings 24 in theunit device. Each device of such .cantahvcr reinforcement is forged,cast or other- Wise formed as a solid steel 'unit, the hub portion 21,.being the central portion of each pair of opposite spoke members 22 and22, is thus formed as a disk of-s'uch size that a sufliciently largeamount of steel can be concentrated in a single layer nearthe upper partof the slab-directly over the ecnterofthe supporting column for thepurpose further set forth. The spoke members22'may be of any desirednumber to the end that-the unit reinforcement shall best fulfil itsoflioe 'hereinai ter described; the openings 24- however being such aswill permit the-concrete to be'easily placed in position around thehu'b, spoke and rim portious of. the device. portion 23' oftlhe devicesin the upper portion-"of Fig. 1. areithe rod members 25 (see Fig. and 27(see Fig. 5.) Which rods extend outwardly. through the flat slab onlines radiating from the axis of the column.

For a. clear understanding of Fig. l. the rods are omitted from 1 theunit devices in the lower=portion of the drawing.

In the flat slab type of floor, it is assumed that a fiat circular plateportion of the slab, fixed t'oa supporting-column, extends out- Wardly'therefrom in every direction, to the line'ofinfiection of the slab, asa cantaliver;

and that the central portion of the flat'slab p'a-nel lies between andis supported; by the outer edges of such column supported cantalivercircular plate portions. In Fig. 8 are seen imaginary cantaliverbeams,.31, passing through the axis of a supporting col-- umn, whoseenlarged head is designated 32*, as in Fig. 2, and the approximatelocation of the line of infiection,'33, of the flat slab has beenplotted. The beams li-l'at Z, Z, extending toward adjacent columnsrectangularly situated, the beams at Y, Y, extending toward diagonalllysituated columns, leaving other beams, 31, extending as at K, tmvardthose portions of the flat slab included between the axcs of adjacentrectangularly and diagonally situated columns.

By reference to Fig. 4, a vertical section is shown", taken through theaxis of a supp rting column, showing a cantaliver beam, such as 31 inFig. 8, reinforced by the continuous steel reinforcing members 22, 21,22 of the unit wheel-like cantaliver device.

If were practical to run rod reinforccn'icnt,

directly over and through the axis of each supporting column, on thelines 31 in Fig. 8, and continue such rod members out through th flatslab on theselines produced. not. cnlyavould the cantalivers themselvesbe ositively reinforced, but tension stresses in the central portion ofthe flat slab would be likewise taken care of. This however wouldnecessitate the rods crossing each Hooked to the rim.

other at the axis of the column, causing them to pile up one on anotherso that the 'ccnter'o'f gravity of the mass of the assembled steel Wouldbe greatly lowered. Since the center of gravity of the steel must benear the surface of the slab over the columns, in order to secure thelongest possib'lemomentarm and thereby obtain the thinnest slabpossible, such radiating rod reinforcement is impractical.

As will be seen in Figs. 4 and 9, the hub or disk portion, 21, of theunit device is formed of such size and character thata sufficient areaof steel is concentrated between the radiating members 22 so that underall conditions, each single 'cantaliver beam 31 in Fig. 8 shall bepositively reinforced by the unit members, 22, 21, 22, to

.the end that the composite plate of concrete and steel shall act as ahomogeneous cantaliver circular plate. The center of gravity of the hubor disk, 21., is, as seen, near the surfaceof the slab over the column,wlnch obviates the impractical feature referred to above-with referenceto radiating rod reinforcement; also, a unit device can thus befabricated in which the radiating members corresponding to suchradiating rod reinforcement are an integral part of one another at theirpoint of crossing, so that. all will act as a unit in the completed.strlu'ture. It would not be practical to make the radiating members 22ofa unit device of. such length as to actually cover the entire panelbetween columns; I therefore prefer tofabricate the unit wheel-likereinforcing devices of such size, that they will approximately cover thecolumn supported cantaliver circular plate; the rods 2.) and 27extending out through the floor slab. are in reality extensions of themembers 22, of the unit device, the member 23, of the device, furnishinga means for transmitting the stresses, carried by the rods 25 and 27directly into the members 22 and to the coin tral hub member 21. Thisthen furnishes in every direction, a continuous reinforcing member, suchas 25, 22, 21, 22, 23. 25 or 27, 23, 22, 21, 22, 23', 27, passingdirectly over and through the center of the supporting column. This is.a very inn'nn'tant fcature of my invention since the stresses beingbrought directly over and to the center of the column, the column is-note'crentrically loaded as it \vouldbe if individual lods radiating tl'ro'ugh 'the slab were merely wrapped around the periphery of the columnor if not run in a straight line from such column axis. Not only do thesupporting columns of a certain loaded panel receive their proper shareof such load, but a continuous monolithic action is produced. portionsof the stresses passing out. froi'n'the central disk or hub portions 21,through the branching members 22 into the rods 25 and other supports, yx

As seenin Figs. Qand l, the unit canta;

panels assist the loaded panel and its supporting columns to carry theload, by transmitting such stresses to outer columns or liverreinforcing devices areshown preterably fabricated 1n a dished fashionbeing inverted in the final disposition of said devices 1n the eombm'edreinforcement, and to".

gether with the rod members are,- as seen in sectiom a proximately onthe line of the catenary. forcing devices, the parts 21 and 23 liepreferably ,in substantially parallel planes, in

order that the connecting intermediate radiatin por'tions 22 may beinclined -or curved 11d thereby more nearly follow the said inc of thecatenary.

In Figs. 2 and 3 are seen rod members 25 with the hools; 26 formed onone end for engagement with the rim 23 of the cantaliver reinforcingdevice as previously stated. The outer end of the rod 25 is seen inFigs. ,1, 2, and 61 passing under the cantaliver device over an adjacentrectangulai-ly positioned column, thereby placing steel in a lower planeover the column head which steel will assist theconcrete'to take thecompression. This willact to reduce the thickness of the concrete overthe entire floor thereby saving in both cost and weight of thestructure.

Tension Stresses exist in-the upper face of the slab between columns onrectangular lines ,due to the deflection there being less '7 than in thecenter of'the slab because of the shorter span. A very important featureof a my invention is seen in the provision I make for caring forsuch'stresses. In Figs. 1, 2,

' land :5 are seen the rod members 27 with the hook-26" formed on oneend for engagement with the rim 23 of the cantaliver reinforcement aspreviously stated. The outer end of the rfo'd 27 is bent into theposition seen in l igz' o forming an'upper portion 28. The

- rods Q'Yflinked tothe rim 23 of the unit device :radia'te therefromoutwardly, the part '28 of the rod 27 being placed in the upper L60. mayact as a true link between all such part or fage of that zone of thefloor slab "extending between columns as seen at 29 in Figs. 1,2 and t.These rods in the completed structure as in Fig. 1, therefore careforthe stresses referred to above, thereby preventing cracking along theedges of the panels fromcolum'n' to column. The total crossfsectionalarea of steel of'all the members 25 and '27 linkedto a rim 23 of a unitde'vice is aphr oximately equal to the area in cross-se'c'tionof allthe'radlating members 22 of such devi'ce,".t0 the end that such deviceradiating members '25 and 27 attached thereto andfprdducea continuousreinforcement in ever i'djii'ecti'on "around the supporting '65 column.r" A vhrticai' section of a completed n these dished shape reinflat slabtaken throughdiagorally situated columns in l ig lz would be similartothe section seen in Fi' 2. omitting the members QStherQinseen t e rodmembers 25 and 27 out by 'siicheec'tioh would be seen lying near thebottom of the slab similar to those shown in section in theeentralportion of Fig; 4.

In the practical application of my invention, in order that eachsutiporting column of a loaded panel shall sustain its properpropbrtionate part of such loading, the rods 25..and 27, While,distributed through the p'a'hels'as seen in Fi Lure Preferably ar rangedso that the inner half of said rods lie nearest the under surface of theflat slab, as

illustrated in the left hand portion oi Fig. l. Where the rod 27 -passesbeneath rods 25 and 27 shown in section, which rods are radiating fromunit devices over adjacent columns. Similarly as this rod '27, thereinseen, passes out into the slab, as shown in the right hand portion ofFig. l. it is slightly raised in order to vpermit the inner half ot therods 25 and 27;,there seen in section, to pass beneath it." Thus lat-anypoint in the Hat slab, the steel rods are preferably arranged in theorder of their distances from their supporting column. Such Weaving ofthe rods mechanically binds them together, making them self-supportingbetween col-v unlns and also preventing displ'aceni'ent during thepourin of the Wet concrete.

To tasteh the ho'oks '26 an'd 26* of the bars 25 and 27 to the rim 28 ofthe unit device in such-a Emanner that the connection at that point willnot be easily *disenga ed during the placing of the concrete as We 1 asto insure that the unit device 20 shall act as a tru'e link between theseveral radiating rods, allowing no slackness in the complete tensi'l'ereinforcement, I may employ 'vari'ou's methods such as electric weldingor Wiring the assembled parts, or I may employ the. ring deviceindicated at 30 in Fig. l. and

. shown in detail in Figs. 6 and 7 wherein a riii 30 is slipped over thehoolr portion 26, an the parts of the hook'26 and the ring 30 driventight against the rim 23 of the unit device 20. Such other modificationsmay beemployed for transmitting the stresses from the rods 25 and 27 tothe unit device 20 as are broperly a ,part of this invention,

the rods 25 anew may be unprovided with the hook portions 26' and. 26*respectively and merely assembled about the device in the lighterconstruction work, but I prefer to give an absolutelyrigid mechanicalbond or tie to the parts as above described.

At the sides of a buildings'tructure 1 prefer to use half unit devicesbuilt into the Wall structure, likewise at the corners a quarter unitdevice would be employed, the

rod members 25 and 27 being run from these fractional devices to eachother and to outer colunihs in inanner seen in Fig. 1.

In Fig. 10. is seen a sheet metal plate With slits 34 and therein, saidslits being made on lines radiating from the center of the plate therebyforming the portions 36 and 37 between said slits and leaving a centralhub portion 38 and band 39 anslitted. I may however employ several.nonslit-ted portions similar to 39. In the periphery or outerband of theplate are made the U shaped slits 40 thereby forming a lip 4-]. Theparts3t5, 37 and -41. are now twisted or bent as seen in Figs. 11 and1:! thereby producing openings 42. 43 and --l"-lin the entire platestructure, the lip 41. being struck up for the purpose hereinafter setforth. During the process of manufacture 1 pret'er to term the platestructure in the inverted dished fashion seen in Figs. 1.2 and 13,

vl n Fig. '13 are seen the hook portions on of the slab rodreintorcement engaging With the unit structural device through theopenings 4A, the lip 4-1 is then driven down upon the hook 26 as seenat- 45, thus firmly attaching the rod member in the desired position.The edge of the unit device may be folded or otherwise thickened as seenat 4-6 which will impart extra strength and stitli'- ness at the .rodengaging parts.

The unit structural reinforcing device seen in Figs. 10, V11, 12 and 1being a modification of the wheeldike unit device seen in Fig. l), isadapted to be used in lieu thereof, and is n'cferably made as seen in lig.

I v n 10 troma rectangular or square plate, in-

which event it would be placed with the corner parts extending to aidthe columns diagonally disposed to the column over which it is situated,thereby substantially occupying the position indicated by the plottedline of inflection seen in Fig. 8. By the expression cantaliver circularplate used by me is meant that portion oi a column supported concreteflat slab, included within the line of inflection, Ill"). 8, the wordtll'cllltll' not being used in its strict sense. The openings 42 and 4?)like 24 in the device-20, Fig. i). permit the concrete to flood aroundthe spoke members 36 and 37. the hub member 38 and the bands or rims3i.) and 4.6; also vertical column reinforcement. may readily passthrough such openings 24 and 42 of the unit devices. Such othermodifications may be en'iployed a. are within the scope of the appendedclaims.

l-laving described my invention, what I new claim as new and desire tosecure by Letters Patent is:

.1. .ln a column supported concrete tint slab or girderless 'tloorstructure, a rein.- torcementcomprising an inverted solid steel, dishedshaped plate ouunit reinforcing device, horizontally disposed over andconcentric with the supporting column,

openings in said device, the parts remaining between said openingsthereby forming a central portionintegrally connected by intermediateradiating portions witha surrounding band portion, situated in a lowerparallel plane, said band-portion lying within the slab without thecolumn, said reinforcing device therebysubstantially covering the.column supported cantaiiver circular plate portion of the slab.

2. in a column supported concrete fiat slab or girderlcss lioorstructure, a reinlorcemeni comprising an inverted, solid steel, dishedshaped plate or unit reinforcing device, horizontally disposed over andconcentric with the supporting column, openings in said device, theparts remaining between said openings thereby forming a central portionintegrally connected by intermcdiat'e'radiating portions with a surlyingwithin the slab, Without the column, said reinforcing device therebysubstantially covering the column supported cantaliver circular plateportion of the flat slab; and members connecting with said surroundingband portion of the device, extending outwardly therefrom on linesradiating from the supporting column, some of said radiatlug membersextending toward and through those portions of the slab lying betweenadjacent. outer columns, and the remainder of said members extendinginto those portions oi" the slab over such adjacent outer columns.

:3. lhdntorcement for acolumn supported coin rctc liat slab orgirder-less floor struc- 'ture. consisting of a number of inverted solidslcel, dished shaped. plates or unit rcinl'orcing devices, each devicebeing horizontally disposed, in the slab, over and concentric with asupporting column, openings in each of said devices, the parts of a de-'vice remaining between such openings constituting a central portionintegrally connected by intermediate radiating portions with asurrounding band portion situated in a lower parallel plane, said bandport-ion lying within the slab without the column, said reinforcingdevice thereby substantially covering the column supported oantalivercircular plate portion of the slab; and. outer rod members connectingwith said surrounding baud portion of the device, extending outwardlytherefrom through the bottom of the slab on lines radiating from thesupprn'ting column, some of. said rods tern'iinating beneath the unitdevices over adjacent outer columns, and the remainder of said rodsbeing bent at their outer ends into the top oi the slab portionsincluded bet-ween opposite outer columns.

-t. A rcint'orcemcnt tor column support.- ed. concrete cantalivercircular plates. comprising a metal plate, slits therein radiating froma central non-slitted portion, and band rounding band portion, said bandportion pox-firms in said. trill portion, to by means said slits; thesesiitted parts having twists i or bends thereby fomnmg opei'ungs Withinsaid plate.

A. perforated unit reinfoii-cing device for concrete constructioncomplislng a. aished shaped. metai. plate having a cen- 'tmi porticniintegraiiy cuni'zootmi with $111 rounding band or rim portions byinterme-' diate portisns formed by slit-ting the plate on linesradiating from the central p rtion, the said intermediate portionsfimnms,

V. MCNUTT.

having twists or bends thereby formlng-openmgs 15

